Binary fission is a method of asexual
reproduction that is employed by most prokaryotes.
In binary fission, the living cell divides into two equal, or nearly equal,
parts. It begins when the DNA of the cell is
replicated. Each circular strand of DNA then attaches to the plasma membrane.
The cell elongates, causing the two chromosomes
to separate. The plasma membrane then invaginates (grows inward) and splits
the cell into two daughter cells through a process called cytokinesis.

Binary fission theoretically results in two identical cells. However, the
DNA of bacteria has a relatively high mutation
rate. This rapid rate of genetic change is what makes bacteria capable of
developing resistance to antibiotics
and helps them exploit invasion into a wide range of environments.

Similar to more complex organisms, bacteria also have mechanisms for exchanging
genetic material. Although not equivalent to sexual reproduction, the end
result is that a bacterium contains a combination of traits from two different
parental cells. Three different modes of exchange have thus far been identified
in bacteria. (See gene transfer.)

Conjunction involves the direct joining of two bacteria, which allows their
circular DNAs to undergo recombination. Bacteria can also undergo transformation
by absorbing remnants of DNA from dead bacteria and integrating these fragments
into their own DNA. Lastly, bacteria can exchange genetic material through
a process called transduction, in which genes are transported into and out
of the cell by bacterial viruses, called bacteriophages,
or by plasmids, an autonomous self-replicating
extrachromosomal circular DNA.